This disclosure relates to low gloss thermoplastic compositions, methods of manufacture thereof and to articles comprising the same. In particular, this disclosure relates to compositions that have low gloss and that contain polycarbonate and acrylonitrile-styrene-acrylates.
It is desirable for certain components used in automobiles to have a low gloss. For example, in automotive rearview mirror housings, a high gloss polycarbonate (PC)-acrylonitrile-styrene-acrylate (ASA) grade is generally used, which demands an additional secondary mechanical operation such as blast treatment to reduce the gloss and to produce a low gloss surface finish. This additional secondary mechanical operation is both time consuming and expensive.
Crosslinked gel concentrates have often been used as low gloss additives for thermoplastic resins. For example, polyepoxides are reacted with polymers containing nitrile groups (e.g., a styrene-acrylonitrile copolymer) to produce crosslinked concentrates that can be added to thermoplastic polymers to reduce gloss. The concentrates of low gloss additives dispersed in polycarbonate or polystyrene resin were blended further with high gloss acrylonitrile-butadiene-styrene (ABS) or polycarbonate-acrylonitrile-butadiene-styrene (PC/ABS) resin mixtures in order to produce ABS-based thermoplastic blends having an inherent matte or low gloss surface finish.
However, the direct addition of the low gloss concentrates to an existing high gloss PC/ASA composition does not produce the desired low gloss characteristics and surface aesthetics. It is therefore desirable to manufacture compositions that comprise polycarbonate and that display low gloss and suitable aesthetics.